Personally I prefer act1 rogue using a "faith"-bow with my wolfs.
But if riches is an issue I would suggest act2 might merc (nightmare offensive.) Equiq him with a reaper's toll and/or CB and leech gear.
Chaos runs; is repeatly running "Chaos sanctuary" (where diablo is) for experience/items....
I think @Elohim's reason for making that clear is that in chaos sanctuary you will encounter mages that curse you/minions/merc with "Iron Maiden" which will return melee dmg to the attacker. Act1 merc's have ranged attack so they are not victim to this.
note: there are better places to lvl your char. so don't make a big deal of it.